Study On Photovoltaic Performance And Its Hysteresis Effects Of CsPbI₂Br All-inorganic Perovskite Solar Cells

CsPbI₂Br perovskite solar cells have become a hot research topic in the past few years due to their excellent thermal stability.However,inorganic perovskite is prone to phase transition and hysteresis at low temperature which is very detrimental to its photoelectric conversion efficiency and stability.The deposition of high quality and high performance inorganic perovskite films with no hysteresis and better stability has been the expectation of researchers.In this paper,we focus on adding a small amount of additives to CsPbI₂Br inorganic perovskite precursor solution to improve the film quality,passivating agent to treat the perovskite surface to reduce the defect density,and suppressing the hysteresis caused by redox reaction to improve its photovoltaic performance.The specific studies are as follows:（1）Dense and smooth CsPbI₂Br thin films were obtained by a one-step solution spin-coating preparation process,and the corresponding all-inorganicvperovskite solar cells were successfully constructed.By studying the effects of three hole transport layers,namely Poly[bis（4-phenyl）（2,4,6-trimethylphenyl）amine],Poly（3,4-ethylenedioxyt hiophene）:Poly（styrene sulfonate）,and Nickel Oxide,on the photovoltaic performance of CsPbI₂Br all-inorganic perovskite solar cells and optimizing the annealing temperature of the perovskite films,the CsPbI₂Br all-inorganic perovskite solar cells based on Ni O_X hole transport layer achieved a photovoltaic conversion efficiency of 9.68%.（2）To study the effect of 1-butyl-3-methylimidazolium tetrafluoroborate（BMIMBF₄）additive on the quality of CsPbI₂Br inorganic perovskite films.It is shown that BMIMBF₄ additive can reduce the defect density of the films and improve the moisture stability of the films in air.The open-circuit voltage,short-circuit current,and fill factor of CsPbI₂Br inorganic perovskite solar cells containing BMIMBF₄additive were also improved,and the photovoltaic conversion efficiency was increased from 9.02%to 10.9%.（3）The use of tris（2-aminoethyl）amine（TAEA）to passivate the perovskite surface to reduce the non-radiative recombination loss,inhibit the hysteresis caused by the redox reaction,and improve its photovoltaic performance was investigated.The mechanism of action is as follows:after treating the perovskite surface with TAEA,on the one hand,it can passivate the defects on the perovskite surface and improve the crystalline quality of the film;on the other hand,it can penetrate into the Ni Ox/CsPbI₂Br interface to passivate the Ni³⁺on the Ni O_X surface to reduce the Ni vacancies and inhibit the hysteresis caused by the redox reaction,and finally the open-circuit voltage and fill factor of the device are significantly improved The final device open-circuit voltage and fill factor were significantly improved,resulting in the increase of the photovoltaic conversion efficiency of CsPbI₂Br inorganic perovskite solar cells from 9.02%to 13.21%.（4）The effect of the combined effect of BMIMBF₄ additive and TAEA passivator on the film quality and device performance was investigated.Using TAEA passivator to treat perovskite films containing BMIMBF₄ additive,we found that the crystalline quality of perovskite films was again improved,the carrier lifetime was extended,and the photovoltaic conversion efficiency of CsPbI₂Br perovskite solar cells was further increased to 13.40%.The results of this thesis provide a way to improve the film quality,reduce non-radiative recombination losses,and suppress hysteresis,which is a reference value for the development of low hysteresis,air humidity resistant,and high performance perovskite solar cells.